From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753645AbaFSMhN (ORCPT ); Thu, 19 Jun 2014 08:37:13 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57504 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751451AbaFSMhL (ORCPT ); Thu, 19 Jun 2014 08:37:11 -0400 Date: Thu, 19 Jun 2014 05:35:53 -0700 From: tip-bot for Rik van Riel Message-ID: Cc: linux-kernel@vger.kernel.org, riel@redhat.com, hpa@zytor.com, mingo@kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, riel@redhat.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, tglx@linutronix.de In-Reply-To: <20140604160942.6969b101@cuia.bos.redhat.com> References: <20140604160942.6969b101@cuia.bos.redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/numa: Ensure task_numa_migrate() checks the preferred node Git-Commit-ID: a43455a1d572daf7b730fe12eb747d1e17411365 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: a43455a1d572daf7b730fe12eb747d1e17411365 Gitweb: http://git.kernel.org/tip/a43455a1d572daf7b730fe12eb747d1e17411365 Author: Rik van Riel AuthorDate: Wed, 4 Jun 2014 16:09:42 -0400 Committer: Ingo Molnar CommitDate: Wed, 18 Jun 2014 18:29:57 +0200 sched/numa: Ensure task_numa_migrate() checks the preferred node The first thing task_numa_migrate() does is check to see if there is CPU capacity available on the preferred node, in order to move the task there. However, if the preferred node is all busy, we would skip considering that node for tasks swaps in the subsequent loop. This prevents NUMA convergence of tasks on busy systems. However, swapping locations with a task on our preferred nid, when the preferred nid is busy, is perfectly fine. The fix is to also look for a CPU on our preferred nid when it is totally busy. This changes "perf bench numa mem -p 4 -t 20 -m -0 -P 1000" from not converging in 15 minutes on my 4 node system, to converging in 10-20 seconds. Signed-off-by: Rik van Riel Signed-off-by: Peter Zijlstra Cc: mgorman@suse.de Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20140604160942.6969b101@cuia.bos.redhat.com Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index fea7d33..8fbb011 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1302,9 +1302,8 @@ static int task_numa_migrate(struct task_struct *p) groupimp = group_weight(p, env.dst_nid) - groupweight; update_numa_stats(&env.dst_stats, env.dst_nid); - /* If the preferred nid has free capacity, try to use it. */ - if (env.dst_stats.has_free_capacity) - task_numa_find_cpu(&env, taskimp, groupimp); + /* Try to find a spot on the preferred nid. */ + task_numa_find_cpu(&env, taskimp, groupimp); /* No space available on the preferred nid. Look elsewhere. */ if (env.best_cpu == -1) {